The jumping spider family
(Salticidae) contains more than 500 described
genera and about 5,000 described species,[2] making
it the largest family of spiders with about 13% of all species.[3] Jumping
spiders have good vision and use it for hunting and navigating.
They are capable of jumping from place to place, secured by a silk tether. Both their
book lungs and the tracheal
system are well-developed, as they depend on both systems
(bimodal breathing).

Behavior

Jumping spiders are generally diurnal, active hunters. Their well
developed internal hydraulic system extends their limbs by
altering the pressure of body fluid (blood) within them. This
enables the spiders to jump without having large muscular legs like
a grasshopper. The
jumping spider can jump 20 to 60 or even 75 to 80 times the length
of its body. When a jumping spider is moving from place to place,
and especially just before it jumps, it tethers a filament of silk
to whatever it is standing on. Should it fall for one reason or
another, it climbs back up the silk tether. Jumping spiders are
Scopula bearing spiders, which means that they have a very
interesting Tarsal section. At the end of each leg they have
hundreds of tiny hairs, which each then split into hundreds more
tiny hairs, each tipped with an "end foot". These thousands of tiny
feet allow them to climb up and across virtually any terrain. They
can even climb up glass by gripping onto the tiny imperfections,
usually an impossible task for any spider.

Jumping spiders also use their silk to weave small tent-like
dwellings where females can protect their eggs, and which also serve as a shelter
while moulting.

Jumping spiders are known for their curiosity. If approached by
a human hand, instead of scuttling away to safety as most spiders
do, the jumping spider will usually leap and turn to face the hand.
Further approach may result in the spider jumping backwards while
still eyeing the hand. The tiny creature will even raise its
forelimbs and hold its ground. It might even jump on the hand.
Because of this contrast to other arachnids, the jumping spider is
regarded as inquisitive
as it is seemingly interested in whatever approaches it.

Vision

The eyes of a female Clynotis severus

Jumping spiders have very good vision centered in their anterior median eyes
(AME). Their eyes are able to create a focused image on the retina,
which has up to four layers of receptor cells in it (Harland &
Jackson, 2000). Physiological experiments have shown that they may
have up to four different kinds of receptor cells, with different
absorption spectra, giving them the
possibility of up to tetrachromaticcolor vision, with sensitivity extending
into the ultraviolet
range. It seems that all salticids, regardless of whether they have
two, three, or four kinds of color receptors, are highly sensitive
to UV light (Peaslee
& Wilson, 1989). Some species (for example, Cosmophasis umbratica) are
highly dimorphic in
the UV spectrum, suggesting a role in sexual signaling (Lim &
Li, 2005). Color discrimination has been demonstrated in behavioral
experiments.

The principal eyes have high resolution (11 min. visual angle)
[1], but the field
of vision is narrow, from 2 to 5 degrees.

Hunting

Jumping spiders are active hunters, which means that they do not
rely on a web to catch
their prey. Instead, these spiders stalk their prey. They use their
superior eyesight to distinguish and track their intended meals,
often for several inches. Then, they pounce, giving the insect
little to no time to react before succumbing to the spider's
venom.

Diet

Although spiders are generally carnivorous, there are some jumping spiders
which include nectar and pollen in their diet[5] and one
species, Bagheera kiplingi, which feeds
primarily on plant matter.[6] None
are known to feed on seeds or fruit. Plants such as the partridge pea offer the
jumping spiders nectar through extrafloral nectaries, and in return
the spiders help to protect the plant by killing and eating
pests.

Reproduction

Male Phidippus clarus in courtship posture

Jumping spiders use their vision in complex visual courtship
displays. Males are often quite different in appearance than females
and may have plumose hairs, colored or iridescent hairs, front leg
fringes, structures on other legs, and other, often bizarre,
modifications. These are used in visual courtship in which the
colored or iridescent parts of the body are displayed and complex
sideling, vibrational, or zigzag movements are performed in a
courtship "dance". If the female is receptive to the male she will
assume a passive, crouching position. In some species, the female
may also vibrate her palps. The male will then extend his front
legs towards the female to touch her. If the female remains
receptive, the male will climb on the female's back and inseminate
her with his palps.[7]

A 2008 study of the species Phintella vittatain in Current
Biology suggests that female spiders react to the male
reflecting ultraviolet B light before mating, a finding that
challenges the previously held assumption that animals did not
register ultraviolet B light.[8] In
recent years it has been discovered that many jumping spiders may
have auditory signals as well, with amplified sounds produced by
the males sounding like buzzes or drum rolls.[9]

Taxonomy and systematics

The monophyly of the
family Salticidae is well established through both phylogenetic and morphological analyses. There is,
however, no consensus on what other group of spiders are most
closely related to the jumping spiders. Suggested sister groups
have included the oxyopids (lynx spiders), thomisids (crab spiders),
clubionoids (sac
spiders), and web building spiders.[10]

Jumping spiders can be divided into three major lineages: the
lyssomanines (subfamily Lyssomaninae), the spartaeines (subfamily
Spartaeinae), and
the salticoids (unranked clade Salticoida).[10]
Of these, Salticoida accounts for over 90% of all jumping spider
species. Salticoida can be further divided into numerous groups
including Amycoida, Astioida, Aelurilloida, Euophryinae, Heliophaninae, Marpissoida,
and Plexippoida.[10]